Process of mounting the dies used as in production of metal threads or wires



TH L TH I March 1930.

OF MOUN DIES TION OF READ F 1 d 15 192 DAS IN PROCES q TING PRODU META i 6 Jan US S OR Patented Mar. 18, 1930 UNITED. STATES PATENT OFFICE GLODIEN ARCHER, OF MEX IMIEUX, FRANCE PROCESS OF MOUNTING THE DIES USED AS IN PRODUCTION OF METAL THREADS OR WIRES Application filed January 13, 1928, Serial No. 246,623, and in France May 9, 1927.

This invention relates to improvements in the process of mounting the dies used as in the production of metal threads or wires.

In the drawing of metal threads of small diameter of the order of 0.2 m. m. the difference in diameter between the entrance and exit of the draw platesis Very small and the plates for ifective operation are very thin being only a out 0.018 m. m.

A very hard material must therefore be used owing to this necessary thinness and a diamond is indispensable if a die having a normal life is required.

The interior forces tending to split the die require the use of Very large stones.

The price of diamonds increases very rapidly with the weight and quality and becomes very heavy for large stones, the price of the dies becoming prohibitive.

The present invention consists in removing this weakness in the stone mounting by hot shrinking of the diamond into a steel holder.

The co-efiicient of expansion of steel being much higher than that of the diamond the contraction of the metal on cooling gives a tight hold upon the stone.

This shrinkage in all directions on to the stone gives rise to compressive forces from the outside inwards which are much larger than the forces due to drawing the wire and the diamond is thus held as securely as the steel holder.

With small stones the hardest metal can thus be drawn without risk of the splitting of the die, a steel die with a diamond core is formed.

The drilling may be done electrically and such an arrangement will be described with reference to the accompanying drawings Fig. 1 is a section through a diamond before setting.

Fig. 2 is a plan the top plate being removed.

Fig. 3 is a section on line 3-3 Fig. 2 the top plate being in position.

Figs. 4 and 5 are a plan and elevation of the anchoring arrangement.

Fig. 6 is an outside elevation of the steel holder.

Fig. 7 is a section showing the diamond ready to be drilled.

Fig. 8 is a section showing the finished die.

Two faces 6 and c of the diamond a are first ground parallel a point d on one of them being selected for the entry of the wire to be drawn. 1

The diamond is then placed with the point d uppermost in the interior 6 of a holder f. The stone should have no lateral play althougl1"'it may be eccentrically mounted if need be to bring the point (Z to the centre of the holder f.

The top of the space 6 is closed with a tight fitting lid 9 of a soft steel giving good electrical contact with the holder, the lid rests on the upper face I) of the stone a.

The holder is held in any suitable clamp. It may conveniently be formed by two semicircular plates h and c' having a peripheral groove along which a wire rope is is passed and twisted at the ends or with lugs and a bolt or in any other manner.

The holder so clamped is inserted into an electric heating apparatus having parallel jaws giving the necessary pressure for operating upon the holder.

The current intensity should be carefully regulated to give a steady heat to soften the top plate of the holder. W'ith gradual tight ening of the jaws of the press the metal is pressed around the stone until the steel compresses and forms two shoulders Z. The melting of the metal must be avoided or the displacement of the stone may occur and also a loss in weight of the stone, this latter being rapidly broken up by molten steel. The heavy pressure is relaxed to allow for the welding together of the materials, the expansion of the holder being prevented by the exterior clamplhe axis of the stone will then be in line with the centre of the holder.

The central point is then readily refound and the usual drilling operations can be performed. If the stone has been displaced the upper face may be stripped to find'the centre again. This stripping as long as it does not affect the centre of the stone is not inconvenient. When the central point is reestablished the holder is turned'about such point Fig. 7,

to cause such point to register with the center of the holder, and when the drilling has been completed the holder is then set (Fig. 8) in a disc m usually of brass for support.

Upon passage of the current, the caps g which have a reduced sectiorr('consequently in which a maximum density of current is established) are heated very rapidly. These caps must reach softening temperature since their material will serve to surround the diamond.

It will be noted that the ends of the caps g in contact with the cold aws of the machine remain hidden, and the cold heads of these caps serve as pistons to fill the soft material in again about the stone.

Due to the rapid heatingof the caps, it is necessary to slow down the operation in such manner that through conductibility the reheating of the molding material 7 is attained.

This part should reach a less high temperature but sufficient, however, to accomplish the welding with the caps g refilled by pressure of the jaws.

As to the ring plates h and i, the density of the current being excessively weak and the ra- I diatlon to the contrary very great, there 1s only a slight heating. This ring therefore preserves all its resistance against the expansion of the mold material 7.

lVhen the whole system is at a suitable temperature, pressure is exerted on the jaws to assure the Welding at the ends of the upper cap and the lower cap. The lateral reaction of the mold material f maintained by the ring plates assures the welding of the whole mounting without leaving a single cavity about the diamond. This welding taking place on the inside of the system is consequently effected without danger of oxidation and is assured of success.

The diamond a embedded, while in heated condition, in steel whose coefficient of dilation is higher, undergoes a strong compression through contraction due to cooling of the metal. I

This rapid process of mounting is not only applicable for setting diamonds in a circular holder but for any stones for dies.

The stones may be set after having been drilled but to avoid molten steel entering the hole this should be filled in with a hard refractory substance such as'a mixture of plumbago or graphite with clay.

the stone, making a central point on one such face, placing the stone in a soft steel holder, closing the top with a plate of the same material, subjecting the holder to heat applied electrically to soften the metal and to pressure to cause it to surround the stone.

In witness whereof I afiix my signature.

GLODIEN ARCHER.

The operations for the preparation of the holder are the same as those for a nondrilled stone the two centres being found and the holder turned so that its centre corresponds with that of the stone. The clearing of the hole of graphite is more readily done if it has been previously polished.

What I claim as my invention and desire to protect by Letters Patent is A process for the setting of diamonds employedas dies for the drawing of metal wire cons'istmg in squaring two opposite faces of 

